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The idea of a missing link between humanity and our animal ancestors predates evolution and popular science and actually has religious roots in the deist concept of the Great Chain of Being. Yet, the metaphor has lodged itself in the contemporary imagination, and new fossil discoveries are often hailed in headlines as revealing the elusive transitional step, the moment when we stopped being “animal” and started being “human.” In The Accidental Species, Henry Gee, longtime paleontology editor at Nature, takes aim at this misleading notion, arguing that it reflects a profound misunderstanding of how evolution works and, when applied to the evolution of our own species, supports mistaken ideas about our own place in the universe.
Gee presents a robust and stark challenge to our tendency to see ourselves as the acme of creation. Far from being a quirk of religious fundamentalism, human exceptionalism, Gee argues, is an error that also infects scientific thought. Touring the many features of human beings that have recurrently been used to distinguish us from the rest of the animal world, Gee shows that our evolutionary outcome is one possibility among many, one that owes more to chance than to an organized progression to supremacy. He starts with bipedality, which he shows could have arisen entirely by accident, as a by-product of sexual selection, moves on to technology, large brain size, intelligence, language, and, finally, sentience. He reveals each of these attributes to be alive and well throughout the animal world—they are not, indeed, unique to our species.

The Accidental Species combines Gee’s firsthand experience on the editorial side of many incredible paleontological findings with healthy skepticism and humor to create a book that aims to overturn popular thinking on human evolution—the key is not what’s missing, but how we’re linked.

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Henry Gee is a senior editor at Nature and the author of such books as Jacob’s Ladder, In Search of Deep Time, The Science of Middle-earth, and A Field Guide to Dinosaurs, the last with Luis V. Rey. He lives in Cromer, Norfolk, England, with his family and numerous pets.

The accidental species : misunderstandings of human evolution/Henry Gee.

pages cm

Includes bibliographical references and index.

ISBN 978-0-226-28488-0 (cloth : alkaline paper)

ISBN 978-0-226-04498-9 (e-book)

1. Human evolution. 2. Human beings. I. Title.

GN281.G36 2013

599.93'8—dc23

2013016599

This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper).

The Accidental Species

MISUNDERSTANDINGS OF HUMAN EVOLUTION

Henry Gee

The University of Chicago Press

Chicago and London

To the memory of John Maddox (1925–2009):

colleague, mentor, and friend,

in the hope that he’d have approved

Contents

Preface: No More Missing Links

1. AN UNEXPECTED PARTY

2. ALL ABOUT EVOLUTION

3. LOSING IT

4. THE BEOWULF EFFECT

5. SHADOWS OF THE PAST

6. THE HUMAN ERROR

7. THE WAY WE WALK

8. THE DOG AND THE ATLATL

9. A CLEVERNESS OF CROWS

10. THE THINGS WE SAY

11. THE WAY WE THINK

Afterword: The Tangled Bank

Notes

Index

Preface: No More Missing Links

Here’s the thing. It’s the curious phenomenon in which otherwise sane and rational news reporters lose all sense of reason or proportion when confronted with anything to do with human evolution, no matter how trivial or (ultimately) inconsequential it might be. Scientists make all kinds of discoveries every day, but almost all add just one small brick to a wall of knowledge that’s sky high. Very few are deserving of any press coverage at all, let alone in the tumescent tones reserved for human evolution. Yet it seems that any paper on human evolution is fair game for the breathlessly orgasmic treatment usually reserved for voice-overs for commercials for expensive ice cream. If all discoveries are treated the same way, one is forced to wonder, then no discrimination can be made between them, and the effect is a kind of dull infantilization in which the significance of the discovery is obscured, and science as a whole is done a disservice.

A recent case was the media brouhaha surrounding the discovery of a fossil primate called Darwinius masillae. If you care to look up the scientific paper in which Darwinius is described, you can—it’s freely accessible to anyone.¹ If you do, you’ll find a perfectly fine description of a rare and beautiful fossil. If you read carefully, you’ll see that Darwinius masillae is one of a number of primates belonging to an extinct group called adapids. Darwinius is a particularly fine specimen of an adapid, but it does not reveal any exceptional insight into the evolution of adapids or of primates as a whole. The evolutionary significance of adapids is debated by specialists, but most agree that they are more closely related to lemurs and bush babies than modern monkeys or apes, let alone humans.

The media circus (there is no other word) implied something rather different—that the fossil represented a crucial stage in human evolution. It was the link. It’s a fair bet that whereas most people won’t have read the scientific paper, with all its technical terminology, they might very well have seen the TV special and accompanying book, launched in a blaze of flashbulbs.

It is partly because of this that I have written this book. My task is to explain why terms such as missing link encapsulate more than a century of error in thinking about evolution, particularly of human beings. They reinforce a monstrous view of evolution whose function is to cement our own self-regard as the imagined pinnacle of creation, the acme, alpha, and omega of evolution.²

Evolution is a word we use to describe changes in organisms due to the interaction of hereditary variation, superabundance, environmental change, and time. Evolution has neither memory nor foresight. It has no scheme, design, or plan. Now, it might be the case that trends, such as one leading remorselessly and finally to the human state, are apparent in evolution, but these are, by necessity, seen after the fact, and are not built into the process beforehand. The patterns we see in life are the results of evolution, and are contingent. In and of itself, evolution carries no implication of progression or improvement. Absolutely none. Zip. Nada.

The term missing link, however, speaks to an idea in which evolving organisms are following predestined tracks, like trains chugging along a route in an entirely predictable way. It implies that we can discern the pattern of evolution as something entirely in tune with our expectations, such that a newly found fossil fills a gap that we knew was there from the outset. Quite apart from the impossibility of knowing whether any particular fossil we might find is our ancestor or anyone else’s, this is a model of evolution that is at once entirely erroneous, and also rather sad.

In my time as fossil-watcher at Nature, the most interest has been sparked by fossils that challenge our expectations, rather than those that confirm them: jolting us out of well-worn mind-sets and forcing us to look at the world in an entirely new way. Fossils such as Sinosauropteryx, the first of many dinosaur species announced that had feathers, or feather-like integumentary structures, prompt us to reassess the evolution of birds and flight; fossils of the aquatic, fish-like amphibian Acanthostega and the amphibian-like fish Tiktaalik compel us to reassess our ideas about how fish evolved legs and left the water; fossils such as Homo floresiensis, with its mute assertion of the unexpected yet likely richness of human diversity in the recent past, show us that there is more than one way to be counted as human.

Whatever its position in evolution, Darwinius was a living organism worthy of study and respect as a creature in its own right; it did not exist by virtue of being a staging post in the predictable evolution of anything else. For that reason, hailing something—anything—as a missing link only cheapens that which we wish to exalt.

In this book I shall show you how and why the view of evolution presented in the popular media is wrong and why we cannot use it to bolster our own position in creation. I shall also show you how to challenge what one reader of a draft of this book has called human exceptionalism—the tendency to see human beings as exceptional by virtue of various attributes such as language, technology, or consciousness. There is nothing special about being human, any more than there is anything special about being a guinea pig or a geranium. This insight should allow you see the world afresh, and marvel at each and every creature as it is, for its innate wonder and uniqueness, not as a way station toward some nebulous, imagined transcendence.

The very beginnings of this book lie with two friends, fellow authors and mentors. The first was paleontologist Chris McGowan. I bumped into Chris in the lobby of the Congress Hotel in Chicago in 1996, where we were both attending the North American Paleontological Convention. I was looking for an agent at the time, and, as I admired Chris’s books, asked him for a recommendation. He kindly gave me the details of his agent, Jill Grinberg, who represents me to this day.

You should write a book about human evolution, Chris suggested, helpfully.

But the World and his Dog have written books about human evolution, I complained—not without justification, as I’d just reviewed a whole stack for the London Review of Books.³ "What the world does not need, I went on, is yet another book on human evolution."

Ah, Chris responded, "but this would be your book on human evolution." This, Chris, is that book. My book on human evolution.

The second was the late John Maddox, editor of Nature, who in 1987 hired me to work on that august, historic magazine as a junior reporter. I was an unlikely candidate, with virtually no writing experience, and I hadn’t yet completed my PhD. But Maddox inexplicably took a shine to me, took me under his wing, and taught me all I know—I owe him an immense debt.

In 1998 Maddox published a book called What Remains to Be Discovered.⁴ As anyone who read the book and knew its author would instantly realize, the book was characteristic—astonishingly erudite (Maddox really did know everything), arch, iconoclastic, exasperating, contrary, and prescient. What set this book apart from the mass (and still does) was Maddox’s conviction—distilled from a lifetime in and around science—that the most interesting things about science are not what we know, but what we don’t know. To go further, it is a fascination with the unknown that motivates scientists. Part of the reason is an intuitive understanding that the more we find out, the more our ignorance grows.

It is a wonder, therefore, that some people—including educators, journalists, and scientists—do not seem to get this. To them, science is all about Facts—like the educational program of Mr. Gradgrind in the opening scene of Charles Dickens’s Hard Times. Facts equate to Truth, and science, they appear to think, is a zero-sum game, all about increasing the quantity of truth and diminishing the net volume of ignorance. In reality, science is about neither Facts nor Truth, but the quantification of doubt. In the small corner of reality that is available to us, scientists set limits on ignorance—but can never banish it entirely. And, to repeat, the more we discover, the more extensive we find the ocean of ignorance. The well-worn response to any new finding—that it raises more questions than it answers—is a cliché for good reason. When I go to talk to scientists about the inner workings of Nature, I announce—with pride—that everything Nature publishes is wrong. This shouldn’t really be as shocking as it is. After all, any answer in science isn’t the Last Word, and indeed can never be so. All scientific discoveries are provisional, set to be overturned by results gained from more data, better instrumentation, and new ideas.

The book proposal I initially sent to Jill was called Dinosaurs Don’t Climb Trees, which morphed into Thirty Ghosts and eventually In Search of Deep Time, in which I aired the idea that knowledge is not a simple matter of accumulating Facts, but circumscribing more nebulous realms of doubt. I didn’t put it in so many words, though—what came out was an exegesis on cladistics, a method of reconstructing evolutionary history that circumvents the assumptions paleontologists and others make about the completeness of the fossil record such that we can reliably read it as a story, in any scientific sense.

That creationists quoted from this book with gusto was perhaps to be expected (I address this issue later on in this book), but what I hadn’t expected were howls of indignation from some paleontologists accustomed to using the records of various organisms as vehicles to infer past history.⁵

As Sam Goldwyn once memorably observed, we’ve passed a lot of water since then. I followed Deep Time with a variety of books, from serious pop-science (Jacob’s Ladder) to fannish criticism (The Science of Middle-earth) to a coffee-table book (A Field Guide to Dinosaurs, illustrated by the incomparable Luis V. Rey) and even fiction (By the Sea and The Sigil)—and yet, despite their variety, all seem to draw from the same inspirational spring. That is, that science begins and ends with an appreciation of the unknown, of the vastness of our ignorance, and that this demands not arrogance but humility before the evidence. This is where, I think, the brave souls attempting to stem the creeping tide of willful (often religiously motivated) ignorance have failed. Rather than trumpeting loudly the virtues of Science, Truth, and—yes—Facts over Pseudoscience and Superstition, they should admit the obvious.

That is, science is not about Truth, but Doubt; not Knowledge, but Ignorance; not Certainty, but Uncertainty. Never in the field of human inquiry have so many known so much about so little. Only creationists, who are vouchsafed the answers at the back of the book (or, in this context, at the front of The Book), can afford the swaddling comfort and deceptive luxury of Truth, of Knowledge, of Facts that can be Known—because they know the answers already, having accepted them without question from a higher authority, as a child from a parent.

Scientists, even those who don’t know their scripture,⁶ who have grown up, so that they feel capable of looking for their own answers rather than having them handed down to them from above, should be able to convey the wonder—the awe, terror, and insignificance—engendered by confrontation with the unknown. That, really, is what all my books have been about, and this one—I hope—represents a distillation of my entire worldview.

Once upon a time we thought the earth was the center of the universe, but were shocked to find that this was not the case. We thought that Man was the pinnacle of Creation, but despite Darwin, many still cling to this view—for which there is neither any excuse nor justification.

1: An Unexpected Party

Many years ago I was a paleontologist. I studied fossil bones. Each bone is mute testimony to the existence of a life, in the past: of an animal the likes of which might have vanished from the earth. I gave up being a full-time bone-botherer when I found myself on the staff of Nature, the leading international journal of science.

I was a junior news reporter on a three-month contract. My first assignment, at 9:30 a.m. on Monday, 11 December 1987, was to write a brief piece on new radiological protection guidelines, of which I knew nothing whatsoever. By noon, however, I was to deliver a well-turned, terse, and, most importantly, authoritative story that could stand the scrutiny of Nature’s discerning readers.¹

It wasn’t long before I accreted the job of writing Nature’s weekly press release—a document that goes out to journalists around the world, keen to learn the latest stories from the frontiers of science. Given that, like me, many journalists would be unlikely to understand all the technical details in each paper, my task was to write a document that would summarize the essence of each in language that would be generally comprehensible. It was an enjoyable and mind-stretching task. On any given day I might be writing about anything in science, from high-energy physics to the molecular biology of HIV-1.

I also got some practice at writing catchy headlines.

My favorite press-release headline concerned a story about mice apt to lose their balance and fall over.² The researchers found a genetic mutation responsible for this defect. The research was important because it allowed an insight into a distressing hereditary disease called Usher’s syndrome, which is responsible for most cases of deaf-blindness in humans, and which can also include loss of balance. To paraphrase what the humorist Tom Lehrer noted about himself, my muse is sometimes unconstrained by such considerations as taste: so my headline was (hey, you’re way ahead of me here)

THE FALL OF THE MOUSE OF USHER

A perk of being the press-release writer was to sit on the weekly meeting of editors trying to decide what would be on Nature’s cover two weeks hence. It was here that I first began to appreciate that editors at Nature are among the first to hear about new insights into the unknown. In 1994, two marine biologists sent us an amazing photo captured by the Alvin submersible at a depth of more than 2,500 meters. The picture was dramatic, contrasty, and gothic. Picked out in harsh spotlights, exposé-style, it showed two octopi, each of a different species unknown to science, but both male, and having sex.³ A colleague suggested that this would make an arresting cover picture—another, however, demurred, on the grounds that it was disgusting. At this point I spoke up—I can still hear myself saying the words—we can always put black rectangles over their eyes. My mind raced ahead, composing an arresting press-release entry that would be headed with the line

BESTIAL SODOMY IN THE ABYSS

In this case, taste intervened and I used something less lurid. The picture didn’t make the cover, either.

I mention all this to excuse some of what follows—if I am critical of journalists and news editors, my criticism comes from experience. I know what it is like to work on a story to a tight deadline, and from a position of relative ignorance. I can also appreciate that the term missing link, which seems to encapsulate so much in so little space, exerts an almost irresistible allure, even though it represents a completely misleading view of what evolution is, how it works, and the place that human beings occupy in nature.

In the course of time, I migrated from the news department to the back half, the team of editors who have the immense privilege of selecting which research papers from the stream of submissions will be published in the journal. One of the pleasures of the job is receiving the first news of important, potentially world-changing discoveries.

An account of perhaps the single most remarkable discovery I’ve seen in my career as an editor was submitted to Nature on 3 March 2004. The discovery was of something quite unexpected, opening up unsuspected vistas on things we didn’t know we didn’t know, and challenging conventional assumptions about the inevitable ascent of humankind to a preordained state as the apotheosis and zenith of all creation. After several revisions, and much discussion among my colleagues and the panel of scientists we’d assembled to advise us on the report of the discovery, the news was published in Nature on 28 October 2004.⁴

This communiqué from beyond the realms of the known came from an international team of archaeologists working in a cave called Liang Bua, on the remote island of Flores, in Indonesia. If you want to find Flores on a map, look up the island of Java, and work your way eastward, past Bali and Lombok, and there it is. Flores is part of a long chain of islands that ends up at the island of Timor, well on the way to Australia, New Guinea, and the Pacific Ocean.

One of the more intriguing questions in archaeology is when Australia was first settled by modern humans, the ancestors of today’s aboriginal peoples. There is much debate about this issue. Clearly, one way of illuminating the problem is to search for early modern humans living in what is now Indonesia, which can be thought of as a series of stepping-stones between mainland Asia and Australia.⁵ That’s where Flores comes in. Archaeologists are interested in the caves of Flores and other islands such as Timor because of their potential to yield remains of Homo sapiens, modern people caught in the act of heading toward that distant island continent later associated with cold lager, Waltzing Matilda, and The Adventures of Priscilla, Queen of the Desert. This is what drew an international team of archaeologists to Flores, and in particular to Liang Bua, known as an archaeological site for decades.

Flores, though, is an island of mysteries—for it has been inhabited for at least a million years,⁶ and not by Homo sapiens. Stone tools have been discovered in several places on the island, and their makers are usually thought to have been Homo erectus, an earlier hominin,⁷ whose remains are well known from Java, China, and other parts of the world. The bones of these early inhabitants of Flores have not been found, their presence betrayed only by the distinctive stone tools they left behind.

But whoever these early inhabitants were, their very presence is a problem. In the depths of the ice ages, when much of the earth’s water was locked up in ice caps and glaciers, the sea receded so far that many of the islands of Indonesia were connected by land bridges—they could be colonized by anything able to walk there. Not so Flores: this remained separate, cut off from mainland Asia by a deep channel. Homo erectus—if that’s who it was—must have made the crossing from the nearest island by boat or raft, or, like other animals, washed up there by accident. Once they made landfall on Flores, there they stayed—cut off from the rest of the world for a very long time.

Isolation on islands does strange things to castaways, making them look very different from their cousins on the mainland. So it was with Flores, home to a species of elephant shrunken to the size of a pony, rats grown to the size of terriers, and gigantic monitor lizards that made modern Komodo dragons look kittenish by comparison.⁸

Such peculiar faunas are typical of islands cut off from the mainland where, for reasons still unclear, small animals evolve to become larger, and large animals evolve to become smaller. Miniature elephants, in particular, were rather common in the ice ages. Practically every isolated island had its own species.⁹ The one on Malta lived eye-to-eye with a gigantic species of swan called Cygnus falconeri, with a wingspan of around three meters.¹⁰ Micromammoths evolved on Wrangel Island in the Russian Arctic, where they outlived their larger mainland cousins by thousands of years.¹¹

The fate of island faunas was an important consideration for Charles Darwin, who marveled at the creatures of the Galápagos Islands in the Pacific Ocean, when HMS Beagle visited in 1835. Darwin noted that each island had its own species of giant tortoise, as well as its own finches—different from one another yet plainly similar to finches from the mainland of South America. Had some stray finches, once marooned on the Galápagos, evolved in their own way?

The scene is set, then, for Flores, where, at Liang Bua, archaeologists surrounded by the bizarre sought for something so seemingly prosaic as signs of modern humans.

What they found instead was a skeleton, not of a modern human or anything like one, but a hominin shrunken to no more than a meter in height, with a tiny skull that would have contained a brain no larger than that of a chimpanzee.

In some ways the skull looked disarmingly humanlike. It was round and smooth, just like a human skull, and with no sign of an apelike snout. In other ways it was a throwback. The jaw had no chin—the presence of a chin is a hallmark of modern humans, Homo sapiens. The arms, legs, and feet of the creature were most odd, looking less like those of modern humans than those of Lucy (Australopithecus afarensis), a hominin that lived in Africa more than 3 million years ago. The big surprise, though, was its geological age. Despite its very ancient-looking appearance, the skeleton was dated to around 18,000 years ago. In terms of human evolution, this is an eyeblink, hardly rating as the day before yesterday. By that time, fully modern humans, having evolved in Africa almost 200,000 years ago, had spread throughout much of the Old World. They had long been resident in Indonesia, and indeed, Australia.

So what was this peculiar imp of a creature doing on Flores, seemingly so out of tune with its times?

Despite the tiny brain, the creature seemed to have made tools. Pinning tools on a toolmaker is very hard (we weren’t there to see them do it), but these tools looked very like those known to have been made on Flores hundreds of thousands of years earlier, presumably by Homo erectus. The only difference was that they were smaller, as if fitted to tiny hands. Had the archaeologists discovered a hitherto unknown species of hominin, dwarfed by long isolation alongside the miniature elephants?

Further work at Liang Bua showed that the first skull and skeleton were no flukes. The skeleton was soon joined by a collection of more fragmentary remains, though no more skulls.¹² All the remains could be